Adaper for `www.googleapis.com/identitytoolkit`

[baltpeter]

We've seen the following endpoint URLs:

• https://www.googleapis.com/identitytoolkit/v3/relyingparty/getAccountInfo
• https://www.googleapis.com/identitytoolkit/v3/relyingparty/signupNewUser
• https://www.googleapis.com/identitytoolkit/v3/relyingparty/verifyCustomToken
• https://www.googleapis.com/identitytoolkit/v3/relyingparty/getProjectConfig
• https://www.googleapis.com/identitytoolkit/v3/relyingparty/verifyPassword

[baltpeter]

API docs for a C# client library: https://developers.google.com/resources/api-libraries/documentation/identitytoolkit/v3/csharp/latest/index.html

[baltpeter]

There are also docs for clients in various other languages (e.g. Go: https://pkg.go.dev/google.golang.org/api/identitytoolkit/v3), which all seem largely identical in terms of content.

They all link to https://developers.google.com/identity-toolkit/v3/, which now redirects to https://developers.google.com/identity/toolkit/migrate-identityplatform. This page is a bit confusing to me. It sounds like these endpoint should have stopped working a while ago:

On June 30, 2020, the SDKs documented on this page and the API setting page will stop functioning. (The https://identitytoolkit.googleapis.com/... and https://securetoken.googleapis.com/... endpoints, used by Identity Platform and Firebase Authentication, will continue to function.)

However, I am still seeing requests to it (https://github.com/tweaselORG/experiments/issues/2 isn't done yet, but I already have traffic from almost 1000 apps to look through). And, importantly, they don't fail but appear to be working just fine, e.g.:

Well, anyway. The API is still functioning and seeing requests, so it's good if we have an adapter.